1. ASTM E60 Committee on Sustainability Workshop on LCA: Methodology, Current Development, and Application in Standards LCA Methodology
Jane C. Bare
November 21, 2018

2. Purposes of an LCA Product Comparison Within company
Between companies (Comparative Assertion)
Baseline Comparison
e.g., 2008 model vs 2009 model
Identify target areas for improvement
Largest source of global climate change impacts
Standards
Goal Setting
Marketing Tool
Meet Consumer Requests

3. Raw Material Acquisition
End of Life
Management
Transportation
Recycle / Reuse
Transportation
Transportation
Transportation
Use / Maintenance
Production

4. LCA includes inputs from nature & multimedia outputs to nature at all life cycle stages
Simplistic Life Cycle of Ethanol Gasoline Blend

5. Framework adapted from ISO 14040 series
Goal and Scope Definition
Interpretation
ID of Significant
Issues
Quality
Assessment
Sensitivity
Analysis
Appraisal
Conclusions
Recommendation
Reporting
Inventory Analysis (LCI)
Life Cycle Impact Assessment (LCIA)
Selection and Definition of Impact Categories
Assignment of LCI results (Classification)
Modeling category indicators (Characterization)
Normalization (Optional)
Weighting Across Impact Categories (Optional)

6. Goal and Scope Definition
Consider the decisions being supported.
Consider the stakeholders involved.
Select a functional unit.
Determine the boundaries in the LCA.
Determine the stages for LCA.
Determine the impact categories included in analysis.
Determine the sources of data for inventory.
Consider level of uncertainty analysis.
Consider how trade-offs will be addressed.
Consider options for improvement.

7. Life Cycle Inventory
Include all inputs from nature (i.e, natural resources modified or consumed) and all outputs to nature (e.g., multimedia emissions).
Consider goal and scope in determining the quality (e.g., site specificity) of the data necessary.
Consider applicability of alternative data sources when data is not readily available.
Make data sources, quality, uncertainty and variability transparent.
Make modeling assumptions transparent (e.g., allocation methods).
Consider running sensitivity analysis for major assumptions (e.g., allocation, unknown inventory data).

8. LCI can consume significant time & effort
Consider hierarchy of data sources based on data quality and applicability.
Sources may include:
Site specific proprietary company data.
Practitioners’ LCA databases.
National LCA databases.
Public data available from other sources (e.g., TRI).

9. Life Cycle Inventory Spreadsheets
VOCs
air
0.00E+00 lb
1.19E+01
CARBON MONOXIDE (CO)
7.47E-04
2.99E+02
NITROGEN OXIDES (NOx)
4.52E-03
2.21E+01
PM10
9.40E-04
6.72E-01
SULFUR OXIDES (SOx)
9.55E-03
2.20E-01
Methane
2.66E-03
NITROUS OXIDE (N2O)
9.22E-06
CARBON DIOXIDE
1.21E+00
1.20E+04
1.39E+01
1 2 4-TRIMETHYLBENZENE
9.40E-03
1.20E-02
1 2-DIBROMOETHANE
1 2-DICHLOROETHANE
1 3-BUTADIENE
8.36E-02
2,2,4-TRIMETHYL PENTANE
3.45E-02
8.03E-01
2,2,5-TRIMETHYL HEXANE
1.08E-02
1.38E-02
2 3 3-tm-Pentane
1.72E-02
2.19E-02
2,3,4-TRIMETHYL PENTANE
1.71E-02
2.18E-02
2,3-Dimethyl butane
2-Methyl-2-butene
7.12E-03
9.08E-03
2-Methyl hexane
1.21E-02
1.55E-02
2-Methyl pentane
2.20E-02
2.80E-02
3-Methyl hexane
1.27E-02
1.62E-02

10. Life Cycle Impact Assessment (LCIA)
Selection and Definition of Impact Categories
Assignment of LCI results (Classification)
Modeling category indicators (Characterization)
Normalization (Optional)
Weighting Across Impact Categories (Optional)

11. This is a diagram of TRACI.
The diagram begins with the inventory. In many cases, the person conducting the study will use data that is available for their site, transport to their site, and for their suppliers if they know that, and then fill in with LCA databases. Data sources and software to gather inventory data can be found at
Note the list of impact categories in the second box. All of these impact categories should be considered unless there is a reason given for exclusion.
Land use and water use are currently under development. I plan on publishing guidance on land use this year and water use next year.
For each impact category the best impact assessment methods were developed for use in the US. The graphic in the top right corner shows eutrophication and demonstrates that the fate and transport is included in the model.
The bottom right box shows that TRACI maintains the independent impact categories without combining them into a single score. After completing a TRACI analysis, the various options can be compared for each of the impact categories.
Further information and papers about TRACI may be found at:
Related papers are available at:
You may contact me for more information or access:

12. Best Decision Points
Midpoint analysis (e.g., ODP, GWP) for ozone depletion, global warming, acidification, eutrophication, and smog formation allows maximum comprehensiveness & scientific defensibility, and minimal value choices & modeling assumptions.
In the previous slide I point out that TRACI stops at the point where each impact category is available independently. Some people would like to continue aggregating the impact categories into one, three, or a smaller number of environmental scores.
This graphic shows how this could be done for the impact category of ozone depletion. The midpoint level, which is the largest rectangular box, is where TRACI stops. There is international consensus on how to calculate ozone depletion potentials. The science is strong leading up to the midpoint level.
If one were to try to calculate all of the possible endpoints and then sum them up into a damage indicator such as Disability Adjusted Life Years (DALYS) or dollars (shown in the bottom left of the screen), one would find out that it is currently impossible to perform science based calculations for all of the endpoints. So in some endpoint/damage models these endpoints drop out, as shown in the bottom right of the screen.
An important point that this slide makes is that impact assessment modeling is often complicated and it is difficult to select an impact assessment methodology without reading about the many assumptions that are made in the development of the methodology.
See the following paper for more details on midpoints and endpoints: Bare, J.C., et al (2000). “Life Cycle Impact Assessment Midpoints vs. Endpoints – The Sacrifices and the Benefits.”
A comparison of impact assessment methodologies is also available: Bare, J.C. and T.P. Gloria. (2006). “Critical Analysis of the Mathematical Relationships and Comprehensiveness of Life Cycle Impact Assessment Approaches.”
The full citation of these and related articles are at:

13. I would like to spend a few minutes on human health cancer, noncancer, and ecotoxicity. Many people would like to include these categories within their impact assessments, but were confused a few years ago because there were different impact assessment methodologies for different countries around the world.
Over the next few slides I will discuss the development and direction of these categories within TRACI.

14. Human Health Modeling
CalTOX was recognized as the most sophisticated model for risk assessment while TRACI was being developed.
Original TRACI based on CalTOX work which uses EPA’s Risk Assessment Guidelines and Human Exposure Factor Handbook.
Provided 23 human exposure pathways with multimedia modeling and Crystal Ball link to allow parameter uncertainty and variability analysis.
CalTOX was used as the original basis model underlying TRACI. When TRACI was developed CalTOX was recognized by the US EPA’s Science Advisory Board as the most sophisticated risk assessment model, consistent with the US EPA’s Risk Assessment Guidelines and the Human Exposure Factor Handbook. It includes 23 human exposure pathways and links with Crystal Ball to allow uncertainty and variability analysis.

15. Parameter Uncertainty & Variability Analysis
Parameter variability: natural variation of input parameters
CalTOX modeling for TRACI including looking at various parameter uncertainty and variability.
Uncertainties can come from places like chemical property data including toxicity data.
Variabilities can be found in the population, meteorology, and surrounding environment.
Parameter uncertainty: random, systematic, and measurement errors

16. Parameter Uncertainty & Variability Analysis From: Hertwich, E
Parameter Uncertainty & Variability Analysis From: Hertwich, E., et al, Parameter uncertainty and variability in evaluative fate and exposure models. Risk Analysis,
Probabilistic research within CALTOX showed that for the majority of the TRI substances chemical data (e.g., toxicity and half life) had the biggest impact on data variability/uncertainty.
This research also supported the theory that toxicity characterization factors could be global.
Shown above are typical results for an uncertainty / variability analysis of TRI substances.
Note that the red bars dominate uncertainty and variability. Red uncertainty parameters included data such as toxicity and half life which were usually the biggest uncertainties for most TRI substances.
The cyan bar displays the variability which is associated with landscape. This would include variabilities in rainfall, soil type, temperatures, etc.
The white bare includes the exposure parameters such as human differences in diet (including fish, meat, and vegetable intake), body weight, age, and other factors which may impact toxicity.

17. Resource Depletion Categories
Although currently not as advanced as many of the traditional pollutant categories.
Resource depletion issues can include:
Fossil fuel depletion
Land use
Water use
Other abiotic resources (minerals)
Other biotic resources (fishing).

18. The question often comes up in LCA: How do you deal with tradeoffs
The question often comes up in LCA: How do you deal with tradeoffs? That is, what do you do when Option A looks better for global warming, but Option B looks better for ozone depletion and eutrophication?
TRACI stops at presenting each of these answers in separate graphs (or file folders). TRACI does not try to sum them up to a single score – primarily because this would involve many value choices to decide the priority or weighting given to the various impact categories.
As mentioned earlier in the discussions on midpoints vs. endpoints, TRACI tries to stay as true to the scientific defensibility as possible. Combining impact categories always involves going beyond the science, however, there are groups that want to use consistent weights to have consistency in their decision making and I will show one of these uses in the next slide.

19. BEES 4.0
BEES (Building for Environmental and Economic Sustainability) takes the TRACI impact assessment and applies a normalization and weighting to come to an overall environmental performance score which is then combined with the economic performance score for an overall score.
BEES users can choose from a number of scoring approaches including one which was developed during a Valuation Workshop in May 2006.
Information and access to BEES can be found at:
Information and access to BEES can be found at:

20. NIST Weighting Workshop
Categorization of stakeholders did matter.
From Gloria, et al, Life cycle impact assessment weights to support environmentally preferable purchasing in the United States. Environmental Science & Technology, (21).
The day began with the stakeholders essentially providing disclaimers and saying that even though they might be a representative from Company X or Government Agency Y, they came in with their individual biases and perspectives based on the media to which they listen, or their previous experiences.
They decided to consider impacts based on a temporal and severity perspective. Those impact categories which might have longer term (even intergenerational impacts) would generally be considered as a higher priority than short term impacts of the same severity.
This may not seem consistent with ozone depletion being listed at the bottom of the list, however, the discussions of the day reflected that many believed that ozone depletion was a problem which was nearly solved.
As you can see, the categorization of stakeholders did matter. Of the nineteen stakeholders in the room, they were divided into categories of LCA experts, users, and producers. All three categories rated global warming as the highest priority impact category.

21. US GBC’s LEED 2009 uses TRACI
“LEED 2009 uses US EPA’s TRACI… because they represent a comprehensive, currently available complement to LEED which is appropriate for the North American building market.”
“Layered on top of the TRACI environmental impact categories are weightings devised under the auspices of NIST…”
“The workbook tool is a credit weighting software program…to assign weights to individual LEED credits. The final weights are expressed as a percentage and each credit point is fed into a typical LEED scorecard to arrive at a sum total of 100 pts for all the activity groups….certified, silver, gold or platinum require a 40%, 50%, 60%, or 80% achievement of pts.”

22. Life Cycle Interpretation
Data Quality / Uncertainty / Sensitivity Analysis
Analysis of tradeoffs.
Initiate an iterative approach focusing on obtaining higher quality data where it matters most.
Can help identify largest areas of impact which may provide greatest opportunities for improvement.
Provide recommendations.
Conclusions and reporting.

23. LCA Issues / Limitations
Goal and scoping is important, but often does not get the focus it deserves since it is early in the process.
Inventory can be time and resource intensive.
Need to be comprehensive in inventory and impact assessment, but data and models are sometimes not available, and consensus does not exist for all models.
Tradeoffs often exist and single scores always involve value choices and assumptions.
LCAs should be transparent including data quality.
Other factors are often involved in decision making.

24. LCA Benefits
More comprehensive analysis can assist in better complex decision making.
Quantification of impacts can put various contributors into context.
Comprehensive view avoids unknowingly shifting impacts to:
Other impact categories
Other environmental media (air, water, soil)
Other life cycle stages
Other geographic regions.
Life cycle tools are making LCA’s easier and cheaper to conduct.